Answer:
<u>The first electronic shell or energy level, having n= 1, called the K shell, is the closest to the nucleus.</u>
Explanation:
In an atom, the sub atomic particles called electrons, revolve around the nucleus of the given atom at different <em>energy levels</em>, called <em>shells</em>.
The energy levels or the electronic shells are denoted by the <em>principal quantum number</em> <em>(n)</em> and has the following values n = 1, 2, 3, 4, 5, 6, 7; <em>from the innermost shell to the outermost.</em>
The electron shells are also labelled by the alphabets, K, L, M, N, O, P, and Q, <em>from the innermost shell to the outermost.</em>
<u><em>Thus the first electronic shell having n= 1, called K shell, is the lowest energy level and is present closest to the nucleus.</em></u>
<u><em>Whereas, the last electronic shell having n =7, called Q shell, is the highest energy level and is farthest from the nucleus.</em></u><u> </u>
